Lung macrophages develop in two different ways

Washington, January 24 ANI A new study has found lung macrophages develop, and these new findings can help reduce organ damage and are important for the continued development of important lung disease treatments.

The research was published in the Journal of Experimental Medicine.

Lung macrophages begin to develop in humans from birth when the lungs are first inflated with inhaled air. In-vivo studies in humans are difficult to conduct, despite the importance of lung macrophages in the immune system.

The researchers at Karolinska Institutet have been able to study the development of human macrophages in a living lung with the help of a model. In the study, it was discovered that lung macrophages develop in two different ways.

In the first type of development, lung macrophages originate from precursor cells already present in the fetus' liver, according to Tim Willinger, associate professor at the Department of Medicine, Huddinge, Karolinska Institutet.

These precursor cells move via the bloodstream from the liver to the lungs. They are exposed to various growth factors in the lungs, which helps them develop into'mature' lung macrophages. The second type of development occurs later in life. He added that they develop from adult precursor cells, so-called monocytes, which are found in the blood.

The researchers also examined whether the origin of lung macrophages affected their function. They could see that lung macrophages, regardless of their origin, had a similar gene expression but with different functions.

The researchers found that fetal precursor cells can divide faster than adult precursor cells, said Elza Evren, a doctoral student in Tim Willinger's research group.

Evren added that the fetal precursor cells fill the lungs faster, which is important early in life to quickly remove microorganisms and other inhaled particles.

The lung macrophages derived from adult precursor cells have been found to be strongly activated by interferon, a protein that has the task to defend against viral infections. It is very likely that this particular type of lung macrophage has an important function within the immune system to help fight viruses.

The researchers were able to see that these lung macrophages are similar to pro-inflammatory macrophages which can become overactivated and contribute to serious lung damage in diseases such as COVID - 19.

The findings contribute to a better understanding of the origin and function of lung macrophages. The researchers identified a potential cell that can be targeted to regenerate tissue-protective macrophages, limit organ damage and promote tissue repair in an injured lung. These findings can support the development of new treatments for a number of lung diseases.

The study was supported by grants from the Swedish Research Council, SciLifeLab, Knut and Alice Wallenberg Foundation, Karolinska Institutet, Centre for Innovative Medicine CIMED Region Stockholm, the Swedish Heart-Lung Foundation, Petrus och Augusta Hedlunds Stiftelse and the Royal Swedish Academy of Sciences.